Penicillin formation by cell-free extracts of Streptomycesclavuligerus. Behaviour of aminoadipyl-modified analogs of the natural peptide precursor δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine (ACV)
- 1 December 1984
- journal article
- research article
- Published by Canadian Science Publishing in Canadian Journal of Chemistry
- Vol. 62 (12) , 2712-2720
- https://doi.org/10.1139/v84-462
Abstract
Six analogs of ACV, the biosynthetic precursor of the penicillin nucleus, were synthesized, in which the .delta.-(L-.alpha.-aminoadipyl) moiety was replaced by: .beta.-(L-aspartyl), .gamma.-(L-glutamyl), .delta.-(D-.alpha.-aminoadipyl), adipyl, glycyl-.delta.-(L-.alpha.-aminoadipyl) and N-acetyl-.delta.-(L-.alpha.-aminoadipyl). The penicillins having the adipyl, glycyl-.delta.-(L-.alpha.-aminoadipyl) and N-acetyl-.delta.-(L-.alpha.-aminoadipyl) side chains were also synthesized. Several improvements were made in earlier routes to ACV and related peptides, including a simplified preparation of a dipeptide precursor, and a new synthesis of .alpha.-aminoadipic acid from lysine. A new reagent, 2-acetoximino-2-phenylacetonitire, was synthesized, which allows ready N-acetylation of amino hydroxyacids in aqueous acetaone at room temperature. The peptide analogs were examined as substrates of the enzyme isopenicillin N synthetase, which converts ACV to isopenicillin N in the presence of O2, ferrous ions and ascorbate. The enzyme was isolated from the prokaryotic organism S. clavuligerus and was employed as a crude salt precipitate or in semi-purified form, freed from other enzymes of the penicillin-cephalosporin pathway. With the crude enzyme preparation, 3 of the analogs are active substrates, i.e., adipyl, glycyl-.delta.-(L-.alpha.-aminoadipyl) and N-acetyl-.delta.-(L-.alpha.-aminoadipyl), but the latter 2 are converted, only via ACV, to isopenicillin N, the normal cyclization product. That the crude enzyme preparation contains a protease that deacylates N-substituted ACV analogs to ACV is confirmed, inter alia, by the behavior of the purified enzyme; of the various analogs, only the adipyl compound is an active substrate, but the conversion of this analog to carboxybutylpenicillin proceeds with only 1-2% efficiency, compared to the natural substrate.This publication has 2 references indexed in Scilit:
- Studies on the ring-cyclization and ring-expansion enzymes of β-lactam biosynthesis in Cephalosporium acremoniumCanadian Journal of Microbiology, 1983
- Clavulanic Acid: a Beta-Lactamase-Inhibiting Beta-Lactam from Streptomyces clavuligerusAntimicrobial Agents and Chemotherapy, 1977